People that liked them think so, but on the other hand people that didn't like them beg to differ. Depends who you ask really.
Personally; Vector Prime didn't grab me at best and left me cold at worst. I didn't bother going on reading the series at the time and it wasn't until years later that I got around to it. . . and then mostly because I'd run out of audiobook alternatives, decided to start listening to the then new LotF series, and thought I may as well catch up on NJO because I thought I'd be lost with all the changes otherwise (I thought right; LotF & FotJ were not exactly easy entry points for new readers.)
In hindsight, I wish I hadn't bothered with any of it. Not that they're all uniformly terrible or anything; they're still (mostly) written by competent authors, but between the meandering arcs, uninspired villains, repetitive character beats, and some bonkers power creep for a certain son of Anakin Skywalker, the whole thing kind of blends together in a grey, mostly forgettable monotone, punctuated but some shockingly terrible ideas. (Seriously, I can't remember what happened from one book to another to save my life, but I can remember several plot turns and "choices" that just struck me as aggressively stupid or hackneyed.)
After getting through all of that (especially that last entry where a geriatric Han & Leia get tortured for no good reason other than probably because the Saw movies were big at the time), putting the EU to bed felt like a mercy killing, at least so far as the mainline books were concerned. IMO the EU was always at it's best when it was telling stories of it's own, away from the OT cast.
